Effect of glucose on endostatin expression in human vascular endothelial cells

[Objective] To study the influence of glucose concentration on expression of endostatin mRNA and protein in cultured human umbilical vein endothelial cells (HUVECs), to demonstrate the characteristics of endostatin (ES) metabolism in high glucose, and thus to explore the possibility of ES to retard the progress of vascular disease complicated with DM. [Methods] HUVECs were cultured in DEME media with or without high glucose and were divided into 3 groups randomly: control group (with 5.6 mmol/L Glu), high glucose groups (with 11.2, 22.4 mmol/L Glu, respectively). After 24, 48, 72 and 96 hours, total RNA and protein were extracted. Semi-quantative RT-PCR and Western blot were used to detect the expression of ES. [Results] The level of ES expression in HUVECs treated with 11.2 mmol/L Glu was increasing with prolonged exposure time at both mRNA and protein levels, especially when the exposure time reached 72 and 96 hours, there was a significant increase compared with control group (P 72 h0.05, P 96 h0.01). When HUVECs were treated with 22.4 mmol/L Glu for 24, 48 and 72 hours, both gene and protein expression of endostatin increased in a time-dependent manner. There was a significant increase in ES expression when they were incubated for 72 hours, but a significant decrease for 96 hours compared with control group (P 0.05). For control group, there was a significant decrease in protein release of ES incubated for 96 hours compared with those for 24 hours (P 0.05), but there was no significant change in expression of ES mRNA during the observed period. [Conclusions] For certain limited period, the expression of endostatin is induced in a time-dependent manner in HUVECs cultured with high concentration of glucose, but it is suppressed with prolonged exposure time. And the reduction in ES expression at both mRNA and protein levels may be part of the reason for those vascular diseases complicated with DM chronically.